Timothy,

AND has a higher precedence than OR, just like * is higher precedence than +. So you need parens in boolean expressions just like you do in algebraic expressions.

A and B or C - evaluates A and B first, then ORs that result with C. If you want the OR to be evaluated first you need parens:

A and ( B or C )

>ah ha, When the line is put alltogether, it becomes one long filter and "(" become necessary. Right? I see now.